Field
This disclosure relates generally to memory systems, and more specifically, to memory systems having an SRAM array and a resistive memory array.
Related Art
Resistive memories, such as magnetoresistive RAMs (MRAMs), are commonly used non-volatile memories. However, read and write access times for resistive memories are typically slow, especially as compared to read and write access times for SRAMs. Therefore, in some systems, non-volatile memory (NVM) backup to SRAM is used. In such systems, an SRAM is used for operation on the data, and upon power down, the data is moved from SRAM to a NVM, such as MRAM. The data is then restored back to the SRAM upon powering up. This solution provides the operation efficiency offered by SRAMs and the non-volatility provided by MRAMs. Such a system may be referred to as a non-volatile SRAM (NVSRAM). In one NVSRAM solution, a bus interface between the two memories is required which must switch during data transfer between the two memories. Alternative solutions includes memory cells which have both volatile and non-volatile portions, but these are area inefficient. Therefore, a need exists for improved NVSRAM system which enables store and restore operations and is area efficient.